Hi
Looking for some advice on repairing an old ESAB LHL 130 arc welder
All 8 Mosfets (IRF450) are blown as well as the 10 ohm gate resistors & P6KE18CA protection diodes.
I've checked the gate control pulses with a CRO & both look good.
All 3 stud mount output diodes test ok & I measure 325V DC across the main capacitor
Can anyone shed some light on the circuit?
I don't quite follow the inverter drive circuit for the main output transformer - do all 8 Mosfets turn on at the same time?
Transformer has no centre tap & there's only 1 - 1000uf capacitor
Is the output only half wave rectified? what's the purpose of the 2 output diodes in parallel?
The IRF450 Mosfets are in a TO-3 case's mounted on 2 large aluminium heat sinks are getting hard to source - has anyone ever tried converting to TO-247 (IRFP450) successfully?
Looking for some advice on repairing an old ESAB LHL 130 arc welder
All 8 Mosfets (IRF450) are blown as well as the 10 ohm gate resistors & P6KE18CA protection diodes.
I've checked the gate control pulses with a CRO & both look good.
All 3 stud mount output diodes test ok & I measure 325V DC across the main capacitor
Can anyone shed some light on the circuit?
I don't quite follow the inverter drive circuit for the main output transformer - do all 8 Mosfets turn on at the same time?
Transformer has no centre tap & there's only 1 - 1000uf capacitor
Is the output only half wave rectified? what's the purpose of the 2 output diodes in parallel?
The IRF450 Mosfets are in a TO-3 case's mounted on 2 large aluminium heat sinks are getting hard to source - has anyone ever tried converting to TO-247 (IRFP450) successfully?